1. Field of the Invention
This invention relates to a method for purification of ethylene compounds having a fluorine-containing organic group, typically a fluorine-containing alkylethylene, and more particularly to a method for removal of impurity iodine compounds from a fluorine-containing alkylethylene.
2. Description of the Prior Art
Fluorine-containing alkylethylenes generally perform an addition reaction with a hydrosilane or a hydrosiloxane extremely rapidly, to give addition reaction products in high yields, and are therefore very important compounds for silicon chemistry.
Such fluorine-containing alkylethylenes are prepared by reacting a fluorine-containing alkyl iodide with ethylene to form a fluorine-containing alkylethyl iodide and reacting the thus formed alkylethyl iodide with an alkali, e.g. potassium hydroxide, as represented by the following reaction formula: ##STR1## wherein Rf is a fluorine-containing organic group.
However, the fluorine-containing alkylethylene obtained in this manner contains traces of the fluorine-containing alkyl iodide, used as the starting material, and the intermediate, fluorine-containing alkylethyl iodide. Where the fluorine-containing alkylethylene thus prepared is used as such for an addition reaction with a hydrosilane or hydrosiloxane, therefore, the fluorine-containing alkyl iodide or alkylethyl iodide act as a catalyst poison, thereby lowering the yield of the desired addition reaction product.